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Cost effectiveness ofnon-structural measures
Some considerations
Chris Zevenbergen
16/032012
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the paradox of optimization
deep uncertainty
context
Content
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Cost-Benefit Analysis New Orleans Flood protection System*
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Rational design of flood protection systems hampered by
uncertainties arisen from:
the influence of climate change on future weatherextreme events;
impacts of large scale disasters.
* Hallegate, Stanford Universty (2005)
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Actual flood risk ?
Risk = P x I
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Actual flood risk ?
?
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Actual flood risk ?
High risk
Risk= constant
Low risk
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Actual flood risk ?
High risk
Risk= constant
Low risk
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Actual flood risk ?
Risk= constant
Low risk
High risk
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Setting the scene: flood risk management
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Current policies in practice (COST C22, 2009): reduce flood probabilities; protection levels do not comply with economic trade-off; extreme events (e.g. overtopping) not taken into account.
Decision makers call for: high ends optimal safety level
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buildings &
networks
Flooding system = Complex Adaptive System (CAS)
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Decision making: options available?
Standards Risk based approach => what do we accept?
Cost Benefit analysis (CBA) => economic optimization Multi-criteria analysis (MCA) => societal consequences
Effect based approaches/ bottom-up=> tipping points New DDS tools (RDM): exploratory modelling Opportunistic/synergistic adaptation
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Costs & benefits: large uncertainties
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Cost Benefits
Construc)on Vic)msavoided
M&O Preventeddamage:
-direct-indirect
1st&2ndordereconomic
benefits
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no one best solution strongly context related deep uncertainty
tend to favor effect based (resilient) approaches need for (new & better) frameworks (social-
economic) for decision makers to be able to act
How to improve sharing of information ? How to scale-up action ?
Conclusions & recommendations